OBJECTIVE:

More than 40% of patients with major depressive disorder do not achieve remission even after two optimally delivered trials of antidepressant medications. This study compared the effectiveness of lithium versus triiodothyronine (T(3)) augmentation as a third-step treatment for patients with major depressive disorder.

METHOD:

A total of 142 adult outpatients with nonpsychotic major depressive disorder who had not achieved remission or who were intolerant to an initial prospective treatment with citalopram and a second switch or augmentation trial were randomly assigned to augmentation with lithium (up to 900 mg/day; N=69) or with T(3) (up to 50 mug/day; N=73) for up to 14 weeks. The primary outcome measure was whether participants achieved remission, which was defined as a score < or =7 on the 17-item Hamilton Depression Rating Scale.

RESULTS:

After a mean of 9.6 weeks (SD=5.2) of treatment, remission rates were 15.9% with lithium augmentation and 24.7% with T(3) augmentation, although the difference between treatments was not statistically significant. Lithium was more frequently associated with side effects (p=0.045), and more participants in the lithium group left treatment because of side effects (23.2% versus 9.6%; p=0.027).

CONCLUSIONS:

Remission rates with lithium and T(3) augmentation for participants who experienced unsatisfactory results with two prior medication treatments were modest and did not differ significantly. The lower side effect burden and ease of use of T(3) augmentation suggest that it has slight advantages over lithium augmentation for depressed patients who have experienced several failed medication trials.